CN1170715C - Method for transmitting data by means of a traction current line for supplying a drive current to a vehicle - Google Patents

Abstract

The object of the invention is to provide a method for transmitting data by means of a traction current line, which supplies a drive current to a vehicle, which reliably prevents an interruption of the data transmission due to an arc occurring between the drive current pantograph on the vehicle side and the traction current line. The object of the invention is achieved by a method for transmitting data (Q) by means of a traction current line (15), wherein at least two data signals with different frequency channels, which always contain the same data (Q), are fed into the traction current line (15) at the transmitting end. In the event of an arc, the receiving party selects from the received data signals the received data of the data signal or of data signals whose amplitude is/are not less than a signal-to-noise ratio required to achieve a defined probability of binary bit errors in relation to the amplitude of the interference signal s (f) for analysis.

Description

Method for transmitting data by means of traction current wires for supplying driving current to a vehicle

technical field

German patent document 730713 discloses a method for transmitting data by means of a traction current conductor, in which the traction current conductor simultaneously carries the drive current of a railway rolling stock. In this method, the data transmission can be carried out both between the rolling stock and between the dispatching station and the rolling stock. In this method, the data is supplied as a data signal to the current-drawing conductor by means of a transmitter on a predetermined frequency channel. This data signal is then transmitted to and received by the receiver via the current-drawing wires. The received data signal is then analyzed in order to obtain received data corresponding to the transmitter data. In this method, the railway rolling stock feeds the data signal into the traction current conductor or receives the data signal by means of the traction current conductor via the drive current pantograph. In this case, the arc generated between the drawing current conductor and the driving current pantograph can seriously disturb the data transmission, and in some cases even cause the interruption of the data transmission, because the data signal is overwritten by the interference signal of the arc The reason.

Background technique

A method is also known from German Patent Application No. 538 650, in which data is transmitted via current-drawing lines. In this method, data signals containing control commands are generated in the first locomotive. In order to transmit this data to the second locomotive, the generated data signal is fed into the traction current line. In this patent document, the data information, ie the individual control commands, are frequency-coded, that is to say each data signal with a predetermined frequency belongs to a control command. In this method, the frequency is adjusted using a joystick in the first locomotive. These data signals go via the traction current conductors to a receiver in the second locomotive, where they are received and evaluated.

Contents of the invention

The object of the present invention is to provide a method for transmitting data by means of a traction current conductor supplying a driving current to a locomotive or a plurality of locomotives, which reliably avoids arcing between the driving current pantograph and the traction current conductor result in interruption of data transmission.

The object of the invention is achieved by a method for transmitting data by means of a current-drawing conductor, which simultaneously transmits drive current to the vehicle, in which method

- supplying at the transmitting end at least two data signals having different channels and containing the same data into the current-drawing conductor,

- where the frequency band determined by these channels is wider than the frequency band of the interference signal expected to be generated by the arc generated between the traction current conductor and the locomotive drive current pantograph,

- data signals are transmitted to and received by a receiver via current-drawing conductors, and

- After the receiver receives these data signals, in order to obtain the received data corresponding to the data of the transmitter, these data signals are analyzed, and when there is an interference signal as a received signal, from the received data signals, select output data for data signals whose channels lie outside the spectrum of the interfering signal determined by the frequency bandwidth.

When the traction current lead is delivering traction current to multiple locomotives, the method of the present invention can also be implemented in the same manner; at this time, it is only necessary to ensure that the frequency bandwidth of the channel containing the data signal is wider than the frequency bandwidth of the expected interference signal caused by the electric arc.

The method according to the invention is distinguished by the fact that data can be transmitted with this method in a particularly reliable manner, since an arc occurring between the current-drawing conductor and the drive current pantograph does not cause interruptions in the data transmission. This is again due to the simultaneous transmission of at least two data signals containing the same data on different frequency channels, that is to say with different carrier frequencies, in the method according to the invention, wherein the frequency bands containing these channels are more than expected arc interference The frequency bandwidth of the signal is such that it is always ensured that at least one data signal transmitted via the current-drawing conductor lies outside the frequency bandwidth of the interfering signal. After receiving the at least two data signals at the receiver, and then analyzing only the data signal or data signals whose channel is outside the interference signal spectrum determined by the frequency bandwidth (interference frequency bandwidth), it is always possible to ensure that the transmission of the data is free from arcing The effect of interfering signals.

In order to achieve a predetermined binary bit error probability (Bitfehlerwahrscheinlichkeit) with a data signal outside the interference frequency bandwidth, the interference frequency bandwidth can be determined, for example, as a function of the amplitude of the data signal, precisely in such a way that the interference The amplitude ratio of the data signal outside the frequency bandwidth to the interfering signal is not less than the signal-to-noise ratio (Signal-RauschaBstand) given by the expected binary bit error probability. Information on these signal-to-noise ratio values can be found, for example, in Dostert, K; Bartel, W.: "New types of data transmission on power supply lines", (elektro-anzeiger 42, Jg. Nr. 12 (1989)).

It can be checked particularly simply and thus advantageously which of the data signals have channels outside the frequency spectrum of the interference signal, that is, at the transmitting end, in addition to sending out the data signal, a check binary digit ( Kontrollsbit), with which it is determined in the receiver whether the data transmitted with the respective data signal has been transmitted without error. Treat data signals that are transmitted without error as being outside the spectrum of the interfering signal.

According to another improved design of the method of the present invention, the data signals with different frequency channels that are preferably odd-numbered but at least three consistent in their logical data content are input in the current-drawing conductor, and the received data signals are analyzed by the receiver. The data are compared with each other, and the data of those data signals for which most of the same data have been transmitted are selected as received data. For this it is of course necessary that the frequency band containing these different frequency channels be at least twice as wide as the frequency bandwidth of the interference signal caused by the arc.

Another advantageous solution for checking the error-freeness of data signals transmitted on a frequency channel consists in the fact that these data signals can only be admitted to have been transmitted error-free if their carrier frequency does not leave a defined amplitude band at a defined time. For example, the requirement can also be increased, that is, only when their amplitude is not lower than 50% of the transmitted amplitude and not exceeded 150% of the transmitted amplitude within the time required for the transmission of a data signal, these data signals are admitted to be transmitted without error. transmission.

The data can be transmitted particularly securely and thus advantageously if the data signals are coded into the current-carrying lines by means of OFDM or spread spectrum methods, since such coded signals are particularly insensitive to interference.

The method according to the invention can be carried out in such a way that data is transmitted from one locomotive to the dispatching station and/or to another or several other locomotives; the data transmission can also take place bidirectionally here. Furthermore, by means of the method according to the invention, data can also be transmitted from a stationary transmitter to a stationary receiving station via a current-carrying conductor subjected to the arc. With the method according to the invention it is also possible to advantageously transmit control signals from the control center to one or more locomotives such as railway rolling stock as data or data signals, so the method according to the invention can be used as a vehicle control method, especially in In the case of railway rolling stock, it can be used as a train automatic control method or a traffic control method.

Description of drawings

The accompanying drawings are used to illustrate the present invention, wherein:

Fig. 1 shows an embodiment of the device that implements the inventive method;

FIG. 2 shows a spectrum of a data signal suitable for data transmission in the embodiment shown in FIG. 1 .

Detailed ways

FIG. 1 shows a railway rolling stock 5 which is connected via a drive current pantograph 10 to a contact conductor 15 as a traction current conductor. A drive voltage Ua is applied to the contact conductor 15 at the drive current feed point 20 , via which a drive current Ia flows through the contact conductor 15 , the drive current pantograph 10 and the drive motor 21 of the railway rolling stock 5 . The return flow of the drive current Ia is ensured by the rail 22 on which the railway rolling stock 5 runs. The drive current feed point 20 and the drive current pantograph 10 or their position define a line section 25 .

At the data signal input point 30 , the data signals D1 to D11 in the form of a data signal current Is are fed into the contact lines 15 by means of a transmitter which can be located, for example, in a control station or a control center. The data signals D1 to D11 each contain the same data Q and reach the railway rolling stock 5 via the drive current pantograph 10 . The return flow of the data signals D1 to D11 or the data signal current Is is ensured by the rail 22 . The data signals D1 to D11 or the data signal current Is reach the selector 55 via the drive current pantograph 10 and then from the selector to the rail 22; this is based on the operation of the drive motor 21 itself or by appropriate design of the drive motor 21 The current filtering circuit has a high resistance to the data signal current Is, so that the outflow of the data signal current Is through the driving motor 21 is negligibly small. Downstream of the outlet of the selector 55 there is an evaluation device 60 which together with the selector 55 forms a receiver 65 of the railway rolling stock 5 for receiving the data signal current Is or the data signals D1 to D11.

The mode of operation of the selector 55 will be described below with the help of an example; in this example, the data of the received data signals D1, D4 and D6 to D11 are the same, and the data of the received data signals D2, D3 and D5 are the same as The data of the received data signals D1, D4 and D6 to D11 are different; this is because the data of the received data signals D2, D3 and D5 are affected by the arc or the are disturbed by the interference signal S(f) caused by this arc and therefore cannot be processed as received data.

In the selector 55, the data of the received data signals D1 to D11 are compared with each other, and the data Q of the received data signals D1, D4 and D6 to D11 are selected as the received data of the receiver 65 and sent to the analysis and calculation device 60. Since the data signals D1, D4 and D6 to D11 contain the same data, their transmission must not be disturbed, so that their frequency channels are always outside the interference spectrum of the interfering signal.

This actual situation can again be explained precisely in conjunction with FIG. 2 . FIG. 2 shows in the frequency range the amplitude spectrum A(f) of the data signals D1 to D11 and of the disturbance signal S(f) caused by an electric arc between the drive current pantograph 10 of the railway rolling stock 5 and the contact conductor 15 . Furthermore, FIG. 2 shows the carrier frequencies f( D1 ) to f( D11 ) of the data signals D1 to D11 . The starting point of the following as an example is that a signal-to-noise amplitude ratio of 6dB should be achieved in order to transmit data. In FIG. When A, the maximum allowable interference amplitude for a signal-to-noise ratio of 6dB. When the signal-to-noise ratio is 6dB, the probability of binary bit error is less than 10-6. It can be seen in FIG. 2 that the interference spectrum of the interference signal S(f) contains two frequency bands Bs1 and Bs2, wherein the data signals falling within those frequencies do not achieve the required signal-to-noise ratio. Specifically, it can be seen in FIG. 2 that the amplitudes of the data signals D2, D3 and D5 with channels, namely carrier frequencies f(D2), f(D3) and f(D5) do not reach the predetermined 6dB signal. noise ratio and thus suffers. In contrast, the other data signals D1, D4 and D6 to D11 have frequency channels or carrier frequencies f(D1), f(D4) and f(D6) to f(D11) outside the two frequency bands Bs1 and Bs2, which The amplitude of λ can achieve a signal-to-noise ratio higher than required, so these data signals D1, D4 and D6 to D11 are not affected by the interference signal S(f).

The embodiment described in conjunction with FIGS. 1 and 2 for transmitting data Q utilizes the recognition that when the frequency band B of the frequency channel containing the data signal is at least twice the frequency bandwidth Bs of the interfering signal S(f) caused by the arc With such a wide range, reliable data transmission is always possible via current-drawing conductors, such as contact conductors, current-drawing rails, etc., even if arcs occur, since the majority of the data signals are now outside the interference spectrum of the arc. Therefore, for this embodiment, for the frequency band B and thus for the carrier frequencies f(D1) to f(D11) of the data signals D1 to D11 must satisfy

B=f(D11)-f(D1)>2*Bs

Wherein, Bs represents the frequency bandwidth of the interfering signal S (f); in the embodiment according to Fig. 2, Bs can be determined in different ways: at first Bs can be determined by summing the frequency bandwidths of two frequency bands Bs1 and Bs2, so for Bs get:

Bs=Bs1+Bs2.

Another way of determining the frequency bandwidth Bs is that Bs is obtained by the frequency difference formed by the maximum frequency of the frequency band Bs2 and the minimum frequency of the frequency band Bs1 , as indicated by the reference symbol Bs in FIG. 2 . Obviously, in the determination method mentioned later, the Bs value is slightly larger than the Bs obtained by the former method, because the Bs value determined by the former method is not included in the frequency range between the two frequency bands Bs1 and Bs2 . However, this has no effect on the feasibility of the described method for transmitting data Q, since Bs determined in both ways guarantees reliable data transmission. The second method for determining the value of Bs can be faster and simpler in practice since the spectrum does not have to be known in detail.

Since electric arcs are generally interfering signals with a wide frequency band, it has proven appropriate in practice to place the frequency band containing the frequency of each channel in the frequency range from about 10 KHz to about 20 MHz, because the frequency band range of the arc Bs max About Bs=5MHz. The distance of the channels from each other is given by dividing the frequency band by the number of utilized channels. The number of data signals or channels is about 128 to 1024 in practice. When selecting the frequency band and channel distance, the condition of the drive current by the pantograph 10 and the influence of the environment (eg rain) are taken into consideration as these may affect the frequency spectrum of the arc.

For example, a binary coded signal, preferably a signal obtained by means of FSK (Frequency Shift Keying) frequency shift keying method, OFDM (Orthogonal Frequency Division Multiplexing) orthogonal frequency division multiplexing method or spectrum spread method, can be used as Data signals D1 to D11 are transmitted. In addition, the control signal can also advantageously be fed into the contact line 15 as data or a data signal; that is to say, the control signal is transmitted to the The railway rolling stock 5, so the method can be utilized as a train automatic control method for transmitting control information to the railway rolling stock 5.

In addition to the use in railway rolling stock, the method can also advantageously be used in trolleybuses, cableways or aerial ropeways.

According to the embodiment shown in FIG. 1, the data signal current Is is fed into the railway rolling stock 5 via the drive current pantograph 10; Railway rolling stock 5. The same applies to the input of the data signal current Is at the control signal input point 30 into the traction current line 15 ; since in principle this can also take place inductively.

Claims (9)

1. method by traction current lead (15) transmission data (Q), by this lead simultaneously to vehicle (5) feed drive electric current (Ia), in the method

-will two have the data-signal (D1 to D11) that different channel (f (D1) is to f (D11)) contains identical data (Q) at least at transmitting terminal to infeed in the traction current lead (15),

-wherein, be wider than the bandwidth (Bs) that is expected at the interfering signal that electric arc produced (S (f)) that produces between traction current lead (15) and locomotive (5) the drive current pantograph (10) by the frequency band (B) that these channels are determined,

-data-signal (D1 to D11) receives to a receptor (65) transmission and by it through traction current lead (15), and

-after receptor (65) receives these data-signals (D1 to D11), in order therefrom to obtain the cooresponding reception data of data (Q) with projector, these data-signals are analyzed, when the interfering signal (S (f)) that occurs as received signal, from the data-signal that is received, select those channels and be in data by the data-signal (D1, D4, D6 to D11) outside the definite interfering signal of bandwidth (Bs) (S (the f)) frequency spectrum.

2. in accordance with the method for claim 1, it is characterized in that: by additional some the verification binary digits that send of transmitting terminal, in receptor, determine whether obtained transmission like clockwork with the data of each data by them; And, with those like clockwork data signals transmitted treat as the data-signal that is in outside the interfering signal frequency spectrum.

3. in accordance with the method for claim 1, it is characterized in that: at least 3 data-signals (D1 to D11) of input in traction current lead (15) with different channel (f (D1) is to f (D11)), wherein, the frequency band (8) that contains channel (f (D1) is to f (D11)) has at least interfering signal bandwidth (Bs) twice so wide; By the take over party data of the data-signal (D1 to D11) that received are compared mutually; Therefrom select the data of those data-signals that great majority have transmitted identical data (Q) as receiving data.

4. in accordance with the method for claim 1, it is characterized in that: the data of selecting the such number data signal that is received are as receiving data, that is, the amplitude of these data-signals is at the width of cloth band that does not leave regulation for data-signal of transmission in the required time.

5. according to the described method of above-mentioned each claim, it is characterized in that: with OFDM-orthogonal frequency division multiplex signal or spread spectrum signal as in data-signal (D1 to D11) the feed-in traction current lead (15).

6. it is characterized in that in accordance with the method for claim 1: data (Q) are transmitted to the receptor of a stationkeeping by a projector of locomotive (5).

7. it is characterized in that in accordance with the method for claim 1: data (Q) are sent to locomotive (5) by the projector of a stationkeeping.

8. it is characterized in that in accordance with the method for claim 1: data (Q) are sent to the receptor of a stationkeeping by the projector of a stationkeeping.

9. it is characterized in that in accordance with the method for claim 1: data (Q) from then on locomotive (5) on the contrary to another row locomotive send or.

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